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Thread: Phase Linear 700 ??

  1. #1
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    Phase Linear 700 ??

    Can a Phase Linear 700 power amp comfortably operate at a four ohm load? Haven't seen much mentioned about these amps, are they desireable and good performers? Are they compatible with different preamps?

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    Senior Member SEAWOLF97's Avatar
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    Quote Originally Posted by midlife View Post
    Can a Phase Linear 700 power amp comfortably operate at a four ohm load? Haven't seen much mentioned about these amps, are they desireable and good performers? Are they compatible with different preamps?
    Commonly referred as "Flame Linear" or "Fuse Linear" for their ability to catch fire while driving a low ohm load ..

    My "other good vintage" speakers are 3 ohm OHMs. When I emailed tech support , the company president answered....He SPECIFICALLY told me NOT to use PL amps with his product as they have been the base for many failures in the past.

    http://www.audiokarma.org/forums/sho...d.php?t=123724

    Phase Linear 700 series amps have some significant technicall differences depending on what exact model and when manufactured.

    Last I knew there was a factory trained tech or engineer in the Washington State area that services and reconditions these.

    These amps can sound very good and have a lot of current.

    They CANNOT be abused or allowed to run hot.

    The entire PL line from this era has earned a reputation for being tempramental and unreliable (with good reason).

    The rudimentary protection circuits are faulty by design and they DO NOT WORK. In the event the amp fails and goes DC there is enough power and current to form a significant FIRE HAZARD.

    Because of this, these amps earned nicknames such as 'Flame Linear' and 'Blaze Linear'

    I understand that this amp was the brainchild of engineer Bob Carver and one of his first commercial successes.

    I used to use 3 of these in commercial applications along with a couple of 400s all through the 80's and finally retired them in the 1998.

    Careful as I am , I had a 400 go up in smoke on me just sitting there idling one day in a monitor application. These are delicate and fragfile amps despite their tough looks.

    I think $500 is high unless it was recently reconditioned by a qualified tech experienced with the speicific issues these units had.

    It is your choice - if you buy it you will probably become a fan.

    whatever you decide, enjoy!

    http://www.talkbass.com/forum/archiv.../t-515095.html


    There are a multitude of amps that are smaller, lighter, better sounding and more reliable than the old Flame Linears. I had 3 400's years ago and all passed DC voltage at one time or another. I have a couple of Crest 7001s that are killer amps. YMMV, of course.

    That made me lol!

    Actually years ago I had a Phase Linear amp I was using with Roland pre and it DID flame out!

    In the middle of a song all of a sudden there was no bass. When I turned around there were flames coming from in between the amp and pre. It went out when I yanked the plug from the wall though.!
    62bass
    02-09-2009, 02:38 AM

    I too have had experience with a new Phase Linear amp going D.C. and destroying several JBL speakers.

    hrgiger
    02-09-2009, 07:49 AM

    Okay this doesn't sound good, flaming linears and all, could you guys who had this problem mention whether you had your amps bridged at all or not? I read a reference to the amps being bridged but I'm not even sure if that's possible (w/ or w/out modification.) Also do you recall what ohm cabs you were running? I read about fuses blowing with 4 ohm loads with bench test signals...

    xbassmanx
    02-09-2009, 09:00 AM

    Okay this doesn't sound good, flaming linears and all, could you guys who had this problem mention whether you had your amps bridged at all or not? I read a reference to the amps being bridged but I'm not even sure if that's possible (w/ or w/out modification.) Also do you recall what ohm cabs you were running? I read about fuses blowing with 4 ohm loads with bench test signals...

    I was running one side @ 4 ohms when mine flamed out.

    and from one of our members:
    http://www.audioheritage.org/vbullet...98&postcount=7

    Couldn't help it, sorry! All of the Fail Liners seemed to reach a point of un-stability sooner or later...700's and 700B's could take out twice as many speakers as a 400. Maybe the home stereo models like you are looking for had enough protection circuits added to make them safer. When we used to use them, they'd be an amplifier one day, smoke show the next. Those 700B's did sound really good, and made plenty of horsepower! Tim
    Bother me tomorrow, today I'll buy no sorrows.
    Doo, doo, doo, lookin' out my back door

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    [quote=SEAWOLF97;254620]Commonly referred as "Flame Linear" or "Fuse Linear" for their ability to catch fire while driving a low ohm load ..

    Yikes

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    Amp technology has come a long way so I make a habit of avoiding old electronics - it is just not worth it for me.

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    Senior Member jcrobso's Avatar
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    I used one for subs in biamped system.

    That was about 15 years ago, 700B ran without problems into 4 ohms, both channels driven. I met Bob Carver shortly after that amp come out, very interesting guy.
    Yes, when working good it is a great amp. However today I would use QSC or Crown.

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    Senior Member jerry_rig's Avatar
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    I think we used to call them Fuzz Linear.

    I bought the top line PL preamp in the mid '70s and returned it immediately. It was unlistenable. I settled for a Harmon Kardon Citation 11 instead.

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    Smile Personal recommendation

    I can easily recommend the use of a vintage Crown Power Amp. I have used DC300AIIs, Power Line Fours and PS-400s with nary a problem for many years.

    They are very stable, rugged and sound very clean. DC300AIIs are available at reasonable prices and make a lot of clean power.

    There are those that say the bad reputation for the PLs is not deserved and cite examples of how they've never had any trouble or that once certain items were fixed or modified, everything was OK. Check the "street reputation" for both PL and Crown and make your decision.

    I have been running Crowns with JBLs for 25 years with no problems ever!

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    I have been running Crowns with JBLs for 25 years with no problems ever![/quote]
    My previous set up was a DC300 with L300s and I thought it worked very well. Had no experience with the Phases so was a bit curious about them.

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    RIP 2010 scott fitlin's Avatar
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    Quote Originally Posted by midlife View Post
    I have been running Crowns with JBLs for 25 years with no problems ever!
    My previous set up was a DC300 with L300s and I thought it worked very well. Had no experience with the Phases so was a bit curious about them.[/QUOTE]I have been using Crown DC-300A,s since 1977, and have had amps fail, on the job, but never took the load with them.

    Today, I still use one DC-300A on my six JBL 2395/2441H, and came back to this amp last year, while overhauling my system, and I had a McIntosh 2125, a Bryston 3B SST, a BGWS 350A, and I even tried a high end McKormack amplifier. Endeavoring to upgrade to higher power levels, AND superior sonic results, I ran this gamut of amps, to replace my tried and true D-150A, and after tiring for one reason or another, I threw the DC-300A on the horns, and VOILA! THIS IS STILL THE SOUND FOR ME! The D-150A,s went up to the tweeters, replacing my Power Line 2,s, and I put my PSA-2,s on 15,s and all was well. NEW Crowns and one big QSC Powerlight 6.0 on subs.

    About Phase linear? Well, all the years, everyone called them everything already mentioned here. I never really had much experience with them, except that I knew many guys who loved PL! In the early 1990,s I was working several clubs on Miami Beach as a DJ! One club, always had gear that looked like it came straight from an Audio Rummage sale. I went to work one thursday evening, i was one of three DJ,s for that night, and when I got to the club the tech was all excited, he had a Phase LINEAR 700B, and he was going to show me how this thing puts a Crown to bed! He was a PL freak. The 700B was driving a pair of JBL 2225H woofers in the booth monitor system, and it didn't sound bad, definitely had some oomph to it. I was the 3rd DJ in the nights lineup, and the 2nd DJ was playing, and pushing the booth monitors hard. We were in the booth around 1AM, and all of a sudden, one 2225 made a loud cracking noise, and I watched that woofers dust cap literally shoot off the cone, and a burst of flame and sparks fly out from the gap area. Like a muzzle flash from a rifle! The amp went to heaven, the 2225 burned to death, and I was going on at 1:30AM with NO monitors!

    This is the stuff the sound pros used to tell us about in the 70,s but I had never seen it happen. As I said, I really had no experience with PL! Back at my main gig, The Warsaw Ballroom, our sound people were doing work one afternoon, and I got into a conversation with one tech, and I asked about the PL, and why it did that? As it was explained to me, the 700B had a massive transformer, and it did, but, it's protection circuitry was not the same way Crown did things. The 700B is DEFINITELY a BIGGER amp than a DC-300A, and it will keep putting out as hard as you drive it. OTOH, the DC-300A,s circuitry will not let you drive the amp to this point. Nonetheless, I saw it and heard it with my own eyes and ears.

    Sonically, I did not think the 700B was as clean, detailed, or punchy as a DC-300A! The 700B did seem to be more powerful but was strictly brute force, not clean audio. As I said, back in the 70,s, many a story told about PL destroying Gauss woofers, and Gauss was considered pretty indestructible!

    Whatever character the PL,s have, to me, is totally offset by the fact that under severe demanding use, they have a habit of self destruction, and taking the load with them. Of course, to be fair, this happens when severely overdriving this amp, BUT, it is this amps overdrive characteristic that everyone I knew that loves them, loves about the 700B!

    IMHO, Crown is a superior sounding amplifier, and a MUCH safer amp to operate!
    scottyj

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    Wow - great story!

    How do you think the 2225 dust cap shot off? Was the VC so hot that it melted the cap glue before it burst into flames? The driver is rear vented; right?

    So the amp was dumping DC into the loads?

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    ...I have an Adcom 200 x 2 amp that was dumping DC into a pair of 4312s. Fortunately, I caught it in time before the tweets got burned.

    The amp is 25 years old but I have had trouble with Denons that are less than 10.

    The Adcom repair was $250 and that is one reason why I don't plan on puting more dough into old electronics. ...basically, you have invested money in an old amp whose parts could go at any time.

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    Senior Member MikeBrewster77's Avatar
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    Quote Originally Posted by scott fitlin View Post
    I was working several clubs on Miami Beach as a DJ ... a burst of flame and sparks fly out from the gap area.
    Hot club!

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    Senior Member SEAWOLF97's Avatar
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    I bought big late 80's BGW amps on the advise of some knowledgeable forumites , rock solid, run cool (375 wpc - 8 ohm..450 @ 4 ohms..very stable on low ohm loads) and not a nonosec of trouble ..and a bargain at going rates.
    Bother me tomorrow, today I'll buy no sorrows.
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    Forget Phase Linear grenades and crusty old Crowns. If you want super quality and at very good prices keep an eye out for Perreuax on Ebay. Here is a 2150.

    http://cgi.ebay.com/Perreaux-model-P...3A1%7C294%3A50

    300WPC into 8 ohms, 500WPC into 4 ohms and it will pump out about 900W bridged into 8 ohms.

    Allan.

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    Junior Member Old curmudgeon's Avatar
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    Talking Good humor

    Quote Originally Posted by Allanvh5150 View Post
    Forget Phase Linear grenades and crusty old Crowns. If you want super quality and at very good prices keep an eye out for Perreuax on Ebay.

    That's funny!

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